05000369/LER-1981-042, Forwards LER 81-042/03L-0.Detailed Event Analysis Encl

Forwards LER 81-042/03L-0.Detailed Event Analysis Encl

ML20009C293
Person / Time
Site:	McGuire
Issue date:	05/06/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009C294	List: 05000369/LER-1981-042, Forwards LER 81-042/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-042-03, /03L-0:on 810406,during Mode 5 Initial Fuel Loading,Seismic Monitoring Instrument Starter Unit Was Not Operating Properly.Caused by Broken Wire & Sensitivity Potentiometer Out of Calibr.Wire Repaired
References
NUDOCS 8107200440
Download: ML20009C293 (3)

LER-1981-042, Forwards LER 81-042/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981042R00 - NRC Website

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DUKE POWER COMPANY Powen Burwxxo 4c2 Socin Cnuncu Srazer, CauntorTE. N. C. asa4a

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ViCE Pat $10ENT 7tt r e.=ose t:Anta 704 ser.- p.ooverio,.

May 6, 1981 273-4o s s

$l- (Ih t.hO Y

Nr. James P. O'Reilly, Director g

U. S. Nuclear Regulatory Commission g/

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f Region 11 7

n ULl 101 Marietta Street, Suite 3100 p

Atlanta, Georgia 30303 JUL 171981* I Re: McGuire Nuclear Station Unit 1

. vis. wc1**g" Docket No. 50-369

'4 y

Dear Mr. O'Reilly:

kl Please find attached Reportable Occurrence Report R0-369/81-42.

This report concerns the operability of the Seismic Monitoring Instrument Starter Unit.

This incident was considered to be. of no significance with respect to the healthandsafetyoqthepublic.

V y truly yours, i

l

,U"-

a. ~

William O. Parker. Jr.

RWO:pw l

Attachment cc: Director Mr. Bill Lavallee Office of Management & Program Analysis Nuclear Safety Analysis Center l

U.S. Nuclear Regulatory Commission P. O. Box 10412 l

Washington, D. C.

20555 Palo Alto, CA 94303 hs<\\

l l

8107200440 810506 PDR ADOCK 05000369 S

PDR

4 McGUIRE NUCLEAR STATION INCIDENT REPORT Report Number: 81-42 Report Date: April 24, 1981 Occurrence Date: April 6, 1981 Facility: McGuire Unit 1, Cornelius, N. C.

Identification of Occurrence: The Seismic Monitoring Instrument, Strong Motion Time-History Accelerograph (SMA-3) Starter Unit (TS-3A) declared inoperable.

Conditions Prior to Occurrence:

Mode 5, Cold Shutdown Description of Occurrence: On April 6, 1981 at 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br />, personnel found that the SMA-3 Seismic Monitoring Instrument Starter Unit was not operating properly. This was discovered while they were performing the monthly pre-1 ventive maintenance checkout on the instrument.

They immediately reported it to the Shift Supervisor who in turn declared the instrument inoperable.

This was a reportable incident pursuant to Technical Specification 3.3.3.3.

Apparent Cause of Occurrence:

The Remote Starter Unit of the SMA-3 System had a broken wire on its transverse axis and the sensitivity potentiometer on its vertical axis was out of calibration.

1 Analysis of Occurrence:

The SMA-3 Seismic Monitoring Instrument is designed to monitor, record and actuate an event alarm in the Operator Aid Computer for any seismic events at the station site.

This system is composed of a central control, recording and playback units, two triaxial remote accelero-l meter units and a triaxial starter unit.

The triaxial starter unit which is located on the containment base slab, sends in signals to the control unit to activate the system at the instant that an acceleration of.01 g or greater is received.

This unit, however, was not actuating the control unit and the event alarm when signals were simulated in the transverse and verti-cal axes during the maintenance checkout (April 6, 1981). Personnel found l

out that this was due to a broken wire on the transverse axis and the l

sens1tivity potentiometer being out of calibration on the vertical axis.

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Safety Analysis

No seismic event had occurred while the SMA-3 monitoring l

instrument was inoperable.

Had there been an event during that time, earth-l quake data would have been gathered and analyzed by several independent seismic monitoring instruments provided in the plant. These instruments are the Triaxial Peak A.elerographs, Triaxial Seismic Switches and the Triaxial Response-Spectrum Re: orders.

Hence, the safe operation of the plant and the health and safety of the public were not affected.

In the event of an earth-quake during normal operation, the unit is shut down if the recorded seismic data exceeds the Operating Basis Earthquake.

The plant's structures, systems, and equipment are then thoroughly investigated.

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1 Report Number 81-42 Page 2

Corrective Action

The broken wire on the transverse axis of the SMA-3 Starter Unit was repaired.

The sensitivity potentiometer on the verti-cal axis was adjusted at the proper setpoint and calibrated.

The Starter Unit was installed and all three channels (axes) were checked for proper operation. The instrument was declared operable on April 9, 1981 at i

1550 hours0.0179 days <br />0.431 hours <br />0.00256 weeks <br />5.89775e-4 months <br />.

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